1. Field Of The Invention
The present invention relates to solid elements and a method for detecting radiation. More particularly, it relates to radiation detecting solid elements consisting of conductive polymers and radiation sensitive materials, and a method for detection by use of the same.
2. Background Art
Recently, electron beams, gamma-, alpha-, beta- and X-rays and neutron beams have been utilized for many purposes in various ways. In order to perform as expected the application of such radiation exposure, it is essential to precisely measure radiation dose.
On the other hand, for the safety of operators who are engaging in such radiation application industries and medical services, it is also very important to detect and measure the radiation quantity at any time. Under these conditions, many kinds of detecting instruments are commercially available to rapidly and sensitively determine various radiation doses.
For example, in a variety of application fields including electron beam processing, cellulose triacetate films are often used for the detecting and measuring elements of the radiation dose which are simple and easy to handle. Because the UV-absorption spectrum of the films vary with radiation exposure, the quantity of radiation exposure can be detected and measured by reading the variation of the absorption coefficient of the characteristic wave length.
Also, the thermal stimulation current measuring method is often used. When the solid is irradiated, an electric charge is generated in accordance with the radiation dose and stored in a trap of the solid. The electric charge is emitted upon a temperature rise, accompanied by evolution of current. The thermal stimulation current measuring method uses this phenomenon. After irradiation, the sample is connected with an external circuit and the temperature is raised at a constant rate. The quantity of electric charge in the sample is evaluated by the amount of current evolved in the circuit. The radiation dose is inspected by the value of the evaluation.
Recently Yoshino et al. have also proposed simpler elements and method for detecting radiation. This method utilizes the fact that the conductivity and absorption spectrum of the conductive polymers remarkably vary by the radiation exposure in a gas including sulfur hexafluoride. [KOBUNSHI RONBUNSHU 41, No. 4,177-182 (Apr. 1984)]
However, the method with cellulose triacetate, for example, requires an UV light source and cannot identify the presence of irradiation by visual inspection and the detection range is 10 Mrad and less.
Further, the thermal stimulation current measuring method requires micro-ammeters to examine the charge emission and results in a large instrument and a long time for estimation. Both methods cannot perform the determination under irradiation and require interruption of the irradiation in order to take out the elements or the sample for measurement.
Regarding this point, the method proposed by Yoshino et al. which uses a combination of the conductive polymers and gas including sulfur hexafluoride, has the advantages of being a simple procedure and a broad range of measurement. And yet the method has the drawbacks of complexity and of restriction for handling the gas, which is a problem during actual use.